First I didn’t mean my post to be a bashing of Form Labs or their current products. I think they make one of the best desktop 3D printers on the market right now. And as a disclaimer I have had issues and am on my second Form1 printer. I do want to say that their customer service has been first rate! Did I mention that their customer service has been great? Because it has.
Yes I agree that confidentiality will severely reduce the number of people able to post what they make. But like basically all printers marketed to the consumer, the accuracy of the part still tends to be poor. The resolution is VERY good which makes for smooth surfaces, but that is not the same as accuracy. The precision, is also very good, but that too is not the same as accuracy. Accuracy is how close to the design dimensions the part ends up at. So a 1" cube should end up printed at exactly 1" if the machine is perfectly accurate. I have used FDM printers that do better than the Form1 in this area, however their surface quality is no where near as good. There is no perfect machine!
Looking at the Tech specs listed (http://formlabs.com/pages/tech-specs) Form labs conveniently fails to mention the accuracy/tolerance of the machine. Based on conversation with others ~1.5% seems to be standard but I would love to hear from Form Labs with an actual number. At any rate this is within most peoples ability to visually say, “Yes that looks right.” however when building gears or other tight tolerance parts 1.5% is not very good at all. Consider a machinist who only worked to such loose tolerances, for a 2" dia gear that comes out to +/- 0.03"! That is considered pretty good for consumer printers, but still bad by machinist standards. Very bad. Even worse if your error on two parts is additive rather than cancelling in nature this can double. Not that I have ever been able to print a truly round shaft, but a 0.5" shaft would still be out by almost 8 thousandths, not exactly round. Based on my experience, I would place positional accuracy no better than 0.4mm when working, but yes I have had two bum units. To further complicate the issue, alcohol and curing can cause some distortion as well. So don’t leave your parts in alcohol or in your curing cabinet for too long.
Yes I could easy print all sorts of demanding objects, but I haven’t seen many people print dimensionally demanding parts with their form one. This is a weakness generally shared by all consumer printers and many industrial printers. As a challenge print a couple of 0.75" dia gears with a 24 tooth pitch. See how they well mesh when mounted on fixed shafts. Or better yet, print a piston and sleeve. Its not so easy! I am sure some of you will succeed in making those, but most probably wont on their first or second try.
I think there are several issues that cause this. The peel process can cause the part to move, fall off etc. as the force involved is surprising large. Perhaps some teflon could be introduced here? Also the laser path does not stay linear as it goes from center, the beam expands slightly and the angle of incidence as the laser beam passes thought the differing materials in the tray causes a non-linear change in angle. Analog PID controls which are much harder to properly set, probably don’t help either. All of that would require a cost increase to fix, so I don’t expect Form Labs to change it.
So yes I do like my printer, but unless my next one works incredibly better than my last two I don’t think I will be considering accuracy the strong point of the Form 1. High resolution, and high accuracy is the holy grail of 3D printing. The Form 1 is a great printer, its just not a perfect printer.